1. Field of the Invention
The present invention relates to a manufacturing method of an actuator and an ink jet head comprising the steps of bonding a piezoelectric film formed on a single crystal substrate to a diaphragm structure member and removing the single crystal substrate therefrom to manufacture the actuator and ink jet head. Particularly, the present invention relates to a manufacturing method useful for forming the actuator and ink jet head with a large area. Also, the manufacturing method can produce actuators and ink jet heads with large areas.
For example, the method can be suitably employed for manufacturing a piezoelectric/electrostrictive film type element, such as an ink jet print head, microphone, an articulator (loud speaker, etc.), various oscillators and radiators, as well as a piezoelectric/electrostrictive film type element which generates bending displacement of unimorph or bimorph type used for sensors, etc. Besides, so-called “element” herein means an element for transducing electric energy into mechanical energy, that is to say, mechanical displacement, stress, or oscillation, as well as an element for transducing reversely.
2. Description of the Related Art
Recently, in the field of optics or precision processing, a displacing element for adjusting optical path or location in the order of submicron and a sensing element for detecting microscopic displacement as an electric change have been desired, and as the answers for that being promoted is the development of piezoelectric/electrostrictive elements such as actuators, sensors composed of such elements that utilize displacement due to reverse voltage effect or electrostriction effect generated when applying an electric field to a ferroelectric piezoelectric/electrostrictive material, and the reverse phenomena.
Now, in an ink jet head, etc., a conventionally known unimorph or bimorph type structure is suitably employed as one of such a piezoelectric/electrostrictive element. In that field, print quality, print speed, etc. of a printer employing such an element has been required to be enhanced, and in order to respond that requirement the development for achieving miniaturization, densification, low voltage driving, high speed response, long multi-nozzle of such a piezoelectric/electrostrictive film type element is still being proceeded.
Moreover, in such a unimorph or bimorph type piezoelectric/electrostrictive element, although reduction in thickness of a substrate composing a diaphragm is considered to be important in order to obtain large bending displacement, generating force, or generation voltage, there remains yet a problem that decrease in strength or deterioration in smoothness occurs because of reduction in the thickness of such a substrate. Besides, there is still another problem in the conventional unimorph or bimorph type piezoelectric/electrostrictive element that reliability is deteriorated due to employment of an adhesive.
In order to overcome these problems, disclosed is in JP 62-213399 A a technology for providing rigid bond strength by means of sintering a piece of piezoelectric ceramics and a ceramic diaphragm together at the same time as a piezoelectric speaker. In this technology, however there have been still problems that optimum designing cannot be achieved by limitation of selecting diaphragm material due to high temperature sintering dissimilar materials and that alignment by precise dimensional tolerance of the order of micron over a large area is difficult due to shrinkage of the diaphragm and the piece of piezoelectric ceramics themselves. Thereby, it was difficult to obtain a highly reliable large area piezoelectric/electrostrictive element (actuator) or an ink jet head.
Further, in JP 11-348285 A, as a method of obtaining an ink jet head by forming a single crystalline piezoelectric film in order to obtain a higher density head, described is a method of utilizing a Pb(Zr, Ti)O3 single crystal film formed on a PbTiO3 single crystal as the ink jet head, and density of a diaphragm fabricated on the piezoelectric film was so poor as to be difficult to obtain a durable head. Further, in JP 2001-113712 A described is a method of manufacturing a long ink jet head using a plurality of MgO single crystal substrates. However, through this method it was difficult to manufacture a higher density head with regard to the gaps between the substrates generated when positioning the substrates. Further, since a large area MgO single crystal substrate cannot be stably manufactured, it was difficult to utilize a single crystalline or unidirectional crystalline piezoelectric film formed on the single crystal substrate for a large area actuator and ink jet head.